The present invention relates to an inspection apparatus using a measuring element such as an inspection apparatus of a stator winding of an electric rotating machine, an arm unit and a cylinder face circumferential moving apparatus. More particularly, the present invention relates to an arm construction and a traveling mechanism suitable for an inspection apparatus for measuring electrostatic capacity of a stator winding in a state in which a rotor is inserted.
There is known in general a type of electric rotating machine having a water-cooled stator winding. Examples of this type are illustrated in FIGS. 29 to 31.
The electric rotating machine shown in FIG. 29 comprises a stator unit 120 comprising a stator 104 formed by inserting and fixing a stator winding (an upper stator winding 103a and a lower stator winding 103b in FIG. 29) in a stator iron core 102 attached to a stator frame 101, and a rotor unit 130 arranged oppositely to this stator unit 120 in a non-contact manner, the rotor unit having a rotor 121, protecting ring 122 and a rotation shaft 123.
Among these components, the stator winding 103 is formed, as shown in FIGS. 30 and 31, by gathering a plurality of strands 105, covering the outside thereof with an insulating layer 106 such as an insulating tape or an epoxy resin, and attaching clips 107 to each end of the individual strands 105. Each of the strands 105 is provided with a hollow hole 108 through which cooling water can flow. These hollow holes 108 communicate to an insulating connection pipe (not shown) and a cooling water duct 110 outside the stator frame 101 through a water inlet port or a water inlet port 109 of the clip 107. Cooling water from the cooling water duct 110 is therefore supplied through the insulating connection pipe and the water inlet port 109 of the clip 107 to the hollow hole 108, and cooling water is discharged through the water inlet port 109 of the clip 107 to the cooling water duct 110.
The individual strands 105, the clip 107 and the insulating connection pipe thus forming a path for cooling water are connected by brazing, and the outside of braze-connected portions is covered with an insulating layer 106 in a manner as described above. The braze-connected portions covered with the insulating layer 106 is subjected to various leakage tests after a strict quality control with a view to preventing leakage of cooling water and thus to assuring reliability. To avoid such inconveniences as partial peeling of the braze-connected portions or pit corrosion caused by vibration, heat cycles and corrosion through service for many years, a coil pressurizing test or a vacuum drop test is usually applied during a periodical inspection to check a change in pressure and thus to confirm the non-leakage state.
However, when cooling water leaks from the connecting portion between the strands 105 and the clip 107, cooling water permeates through the insulating layer 106 at the portion covered with an insulating tape by capillary action, and particularly when cooling water permeation reaches the stator iron core 102, an inconvenience known as a ground-fault may occur between the stator winding 103 and the ground. It is therefore believed to be important to pay sufficient attention to permeation of cooling water into the insulating layer 106 and check it up as early as possible.
As a method for such a checkup, there is proposed a method of inspection, paying attention to the difference in specific inductive capacity between the insulating layer 106 and cooling water, which comprises determining a corroded stator winding resulting from absorption of water by the insulating layer caused by cooling water leakage by measuring electrostatic capacity through application of a measuring element to measuring positions P and P (see FIG. 29) of the stator winding.
In the checkup method of determining the corroded stator winding resulting from absorption of water by the insulating layer caused by cooling water leakage, however, the measuring position of the stator winding to which the measuring element is applied is located at a depth in the electric rotating machine or the human hand is unreachable in the state as it is. It is therefore necessary to perform an inspection by pulling out the rotor unit from the stator unit.
The operation of thus pulling out the rotor unit requires much labor for dismantling, takes much time, and is not always efficient. Furthermore, because inspection of the stator winding including the operation for pulling out the rotor unit is carried out by stopping the electric rotating machine, a longer inspection period leads to a higher cost.
The inspection carried out after removal of the rotor unit also requires direct use of human power in pressing operation of the measuring element, and is not therefore always efficient.
Because, for example, the measuring element has usually a rectangular shape, there may be a change in the effective area of the measuring element, depending upon the direction of pressing, resulting in easy occurrence of fluctuations of measured data. In order to obtain satisfactory measured data, it is necessary to press the measuring element while causing the same to follow the curved and other surfaces of the stator winding, and it is difficult to carry out this pressing operation within a limited space.